A cogeneration system supplies generated electric power to users for electric power loads and recovers and stores exhaust heat for hot water supply loads of the users, the exhaust heat being generated by the electric power generation. Known as this type of cogeneration system is a cogeneration system configured such that a fuel cell and a water heater operate by the same fuel (see PTL 1, for example). A cogeneration system disclosed in PTL 1 includes: a fuel cell; a heat exchanger configured to recover heat generated by the operation of the fuel cell; a hot water tank configured to store water having flowed through the heat exchanger to be heated; and a water heater configured to heat the water flowing out from the hot water tank up to a predetermined temperature, and is configured such that the fuel cell and the water heater operate by the same fuel.
Moreover, a fuel cell power generation apparatus provided inside a building is known, which is configured for the purpose of improving an exhaust performance of the fuel cell power generation apparatus (see PTL 2, for example). A power generation apparatus disclosed in PTL 2 is a fuel cell power generation apparatus provided and used in a building including an intake port and includes an air introducing port through which air in the building is introduced to the inside of the fuel cell power generation apparatus, an air discharging pipe through which the air in the fuel cell power generation apparatus is discharged to the outside of the building, and a ventilation unit. The ventilation unit introduces the air from the outside of the building through the intake port to the inside of the building, further introduces the air through the air introducing port to the inside of the fuel cell power generation apparatus, and discharges the air through the air discharging pipe to the outside of the building.
Further, a power generation apparatus including a duct extending in a vertical direction is known, which is configured for the purpose of improving the exhaust performance of an exhaust gas generated by a fuel cell provided inside a building (see PTL 3, for example). In a power generation apparatus disclosed in PTL 3, a duct extending inside a building in a vertical direction and having an upper end portion located outside the building is a double pipe, and a ventilating pipe and an exhaust pipe are coupled to the duct such that an exhaust gas or air flows through the inside or outside of the duct.